[Mesa-dev] [PATCH] i965: Avoid dependency hints on math opcodes

[Mike Stroyan]

 On Wed, Mar 19, 2014 at 3:16 PM, Matt Turner <mattst88 at gmail.com> wrote:
> - Does the broken behavior depend on the hardware generation? I.e.,
> broken on Ivy Bridge and Haswell but not Ironlake?
> - There are ~12 math ops. Are the dependency control hints broken for
> all of them, or just exp2?

The problem with NoDDClr and NoDDChk are the same on Ivy Bridge and Haswell.
It doesn't happen with Ironlake because compiling for Ironlake uses send
instead of math opcodes.
Using send means that it also avoids using NoDDClr and NoDDChk.

Mutating my piglit shader_runner test shows the same problem occurs for
math with exp2, log, rsq, sqrt, and sin.
I didn't create test cases for the two operand opcodes.  But I am not
optimistic about them.

-- 

 Mike Stroyan - Software Architect
 LunarG, Inc.  - The Graphics Experts
 Cell:  (970) 219-7905
 Email: Mike at LunarG.com
 Website: http://www.lunarg.com
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